National Dental Examining Board of Canada (NDEB) Practice Exam 2026 - Free NDEB Practice Questions and Study Guide

Calcium sulfate dihydrate can be added to decrease the setting time of stone and plaster because it acts as a retarder, slowing down the setting process. This gives the user more time to properly mold and shape the material before it hardens. Potassium sulfate, boric acid, and magnesium oxide all act as accelerators, which would speed up the setting process and potentially make it more difficult to work with the material.